math - Java check if two rectangles overlap at any point

Question

I have multiple rectangles and one special rectangle: the selection rect. I want to check for each rectangle if the rectangle contains at least one point which is inside the selection rectangle. Here is an image for clarity:

Answer 1

Background:

A rectangle can be defined by just one of its diagonal.
Let's say the first rectangle's diagonal is (x1, y1) to (x2, y2)
And the other rectangle's diagonal is (x3, y3) to (x4, y4)

Proceeding:

Now, if any of these 4 conditions is true, we can conclude that the rectangles are not overlapping:

1. x3 > x2 (OR)
2. y3 > y2 (OR)
3. x1 > x4 (OR)
4. y1 > y4

Otherwise, they overlap!

Alternatively:

The rectangles overlap if

(x1 < x4) && (x3 < x2) && (y1 < y4) && (y3 < y2)

Sample solution on Leetcode: https://leetcode.com/problems/rectangle-overlap/discuss/468548/Java-check-if-two-rectangles-overlap-at-any-point